1. Field of the Invention
The present invention relates to an internet based telephone, and more particularly to an internet based telephone apparatus adapted to enable a communication with a general analog telephone (hereinafter referred to as general telephone) through a public switched telephone network and with another internet based telephone through an internet network, and a communication between a general telephone connected via a public switched telephone network and a still another internet based telephone connected via an internet network.
2. Description of the Prior Art
The most important communication means in our daily life these days is telephone, and particularly, the telephone enjoys the highest position in communication with distant relatives or friends, or in business communication. However, an international communication, a general telephone combined with internet, so called “internet phone” is slowly replacing the general telephone.
The internet phone in practical use now can be largely classified into PC-to-PC, and PC-to-phone, and the most beneficial merit of the internet phone is that utility rate thereof is reasonably cheap, which is realized by packet transmission method.
Furthermore, the internet phone, utilizing a public internet network can provide service by connecting an internet dedicated line to an Internet Service Provided (ISP) and installing an internet phone equipment, such that service can be offered at a much lower investment capital compared with existing public telephone network even in network set-up.
An initial internet phone is a method by which voices are exchanged PC and PC are connected through an internet network and through microphone and speaker (headset), which was developed by vocaltes. The vocaltec method is that two people wanting to communicate via telephone connect to internet at the same time and communicate by connecting to internet server of voclatec through an identical program of vocaltec. At this time, an analog voice signal input from a microphone is changed into a digital signal at a program in PC and compressed (64K compressed to 5.3K, 6.3K and 8K by G723, G729 method), where, a voice signal packeted by utilizing transmission protocols such as H.323, RSVP, RTP/RTCP and the like is sent to PC of the other party through the internet network per packet, and the voice signal is programmatically decompressed by the PC of the other party to change the digitalized voice signal to analogue voice signal and to restore the voice through a speaker for communication therebetween.
However, communication quality of the PC-to-PC method has not achieved an expected result due to varied PC performance, state of internet line, performance of used program and the like. Still worse, there are other problems in that same program should be used by two people wanting to communicate and time should be pre-arranged for use of internet phone between the two limiting a full-scale use of the internet phone era.
As a result, a method has been developed connecting PC with a general telephone, that is, a corresponding program is installed at a PC to be connect to an internet network, and is again connected to Public Switched Telephone Network (PSTN) via equipment known as Internet Phone Gateway installed at a specific area to communicate with the general telephone (a telephone used in home and office via PSTN).
This method can be regarded as a much improved version in comparison with PC-to-PC method in that receiving party can communicate through the general telephone although a person communicating through PC can speak in the same way as that of PC-to-PC method. The aforementioned PC-to-PC method is all realized by internet method while the PC-to-phone method uses the internet method on the calling party and the existing telephone method on the receiving party. In other words, the IPG serves to connect the internet with the existing public telephone network.
However, there is a problem in that the existing public telephone network is used up to the receiving telephone, such that a calling person or a communication-brokering person should pay telephone charge for using the corresponding telephone network. There is another problem in that PC-to-phone method cannot be connected to the internet phone at the general telephone side.
In other words, the PC-to-phone method is beyond its capacity in replacing the existing telephone. After all, in order to substitute the current telephone method, phone-to-phone method is only alternative measure, and the phone-to-phone method calls for installation at corresponding area of Gateway for connecting the telephone network with internet network in order to use PC side of the abovementioned PC-to-phone method as telephone. That is, connection is made is order of public telephone network-internet-network-public telephone network for communication via telephone which can be embodied by the Gateway for enabling network connection between each network and signal detection. Because of this, equipment development named as internet phone Gateway is regarded as being important with program on PC no longer being considered as such, such that world renowned switchboard development companies are embarking on development of the Gateway. There still remain may things to be solved such as equipment of excellent performance, large capacity of internet backbone network, further advanced protocol and the like. However it is questionable whether to place an international telephone call at a city phone rate because the telephone-to-telephone method for embodying the internet phone by way of general telephone calls for installment of high-priced equipment named as internet phone Gateway.